Insoo Hyun, a bioethicist at the Case Western Reserve School of Medicine in Cleveland, Ohio, followed with a perspective piece in PLOS Biology, stating that the benefits of this kind of research are so great that we should no longer hesitate to fund it.

The piece by Hyun addresses traditional concerns in animal ethics, such as safety, the moral status of the non-human animal (in this case, the human/non-human chimera) and the exploitation of non-human animals in research.
We agree with his precautionary stance which, is consistent with the existent ethical standards for chimera research developed by the Internal Society for Stem Cell Research in 2007, and with more emphasis on animal welfare than on speculative concerns about moral humanization of the human/non-human animal chimera.
Ultimately, we find that Hyun's conclusions that 'most, if not all, of these [traditional] concerns can be reasonably addressed' are plausible.However, Hyun fails to address the elephant in the room: why should we invest significant resources in the creation of humanised animal models in the first place?

Let's take a look at the two main assumptions in Hyun's piece.
First assumption:

He adds: 'The humanitarian importance of this research is both apparent and urgent. There is currently a dire shortage of organs for transplantation in the United States, leading to approximately 22 deaths per day among patients waiting for organs.' (Hyun 2016, 2).

Hyun is right about the numbers, but we believe that the urgency of the research is not by any means self-evident. What he fails to examine is whether the creation of humanised animal models is the best way to address this pressing matter, and he fails to acknowledge the existence of viable alternatives, such as opt-out policies to increase organ donation from human to human, (one example notable is Austria with an organ donation rate higher than 90 %; and in the UK a similar law was approved in Wales in December 2015.

Second assumption:

'Given the noble aims of this research, it is puzzling to some why the NIH is so nervous about providing federal funds to researchers with a track record of success in this area.' (Hyun, p. 2)

When put in this way, it is difficult to object to research that aims to save lives and relieve suffering. The argument goes - We have the opportunity to save lives and we should do that. If we fail to do that, we are equally morally responsible (acts and omissions are morally equivalent). Such beneficence-based arguments are common patterns of moral argumentation about new and emerging science and technologies, but they risk to uncritically accept scientists' assumptions. In this case, the assumption being that the research has the noble aim of solving the shortage of human organs, and as along as precautionary measures are taken to ensure safety, and respect for the welfare the animals, then research should be allowed to go ahead.

In the UK, any research of this kind would need a specific licence granted on a case-by-case basis from the HFEA. In 2007, two research groups in the UK (the Stem Cell Biology Laboratory directed by Dr Stephen Minger at King's College London, and the group headed by Dr Lyle Armstrong at Newcastle) applied independently for a license to the HFEA to carry out interspecies somatic cellular nuclear transfer for the creation of 'cybrids', which were eventually granted after a period of deliberation and public consultation.

It remains to be seen how much funding research groups working on humanised animal models for organ transplants will be able to attract. But at these early stages of deliberation, it is important to reflect that investing in this research is a deliberate choice that will shape our collective future. By choosing to invest in this kind of research, we are actively deciding how to allocate scarce resources to address the social problem of shortage of human organs for transplants.

While we do not necessarily believe that the existence of viable alternatives should be used to ban humanised animal models outright, it is certainly a matter that deserves ethical attention. We need reflect on the fact that, by ignoring other potential solutions - or at least prematurely supporting one solution over another - we are actively privileging a medical/scientific solution over a political solution of devising and implementing policies to facilitate human-to-human transplants.

Historical reasons to be skeptical of scientific/medical solutions to a social problem abound. The appealing trend of using technology to fix a social problem, (e.g. sterilization of parts of populations considered a burden to society instead of investing of disability accommodations; the widespread use of Ritalin and Adderall to manage unruly children in schools instead of investing more resources in education; the use of high-income countries pharmaceutical solutions to epidemics in low-income countries which could be solved with basic public health measures) is problematic and needs further critical reflection. Technical feasibility alone should never be driving a change in law and policy.